Question
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For a residue hydrotreater, feedstock about 360C+, what would be accaptable values for TI (toluene Insoluble) following ASTM D 4072? We encounter often pressure drop issues in the first reactor and we would like to sample the feed mix for TI. But there is no guideline what is acceptable and what is too much. Any idea?
Sep-2023
Answers
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Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br
This a very interesting topic which is really hard to find a conclusive limits in the literature. Despite this, it's possible to find some publications quoting 1,0% in mass as a very high value to toluene insoluble material for extra-heavy crudes and it's possible to understand, based in some publications, which an adequate value would be below of 0,1 % in mass, but it's necessary to analyse this critically once is based only in the available literature.
Regarding the pressure drop issue in the residue hydrotreater reactors it's important to analyze the composition of the feed to help to understand the origin of solid particles which is responsible for the pressure drop, if the processing unit is processing bottom feed streams from FCC it's possible that ash content in the feed is high due to catalyst losses which highly contribute to the pressure drop raising and shorter lifecycle of hydroprocessing reactors. Another strategy is to blend the feedstock with lighter fractions (if available) in order to improve the solubility limit of the asphaltenes once when this limit is reached asphaltenes starts to aggregate and then starts coking deposition due to the separation from the oil phase.
Sep-2023
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